Patent Application
20150083112
This disclosure relates generally to heliostats having reflectors configured to redirect sun light to a target or receiver, and in particular to the mechanical interface between a heliostat drive assembly configured to orient the reflector and the structure upon which the drive is mounted.
In Concentrating Solar Power (CSP) plants, arrangements of heliostats reflect sunlight toward a receiver mounted atop a tower containing a working fluid. One type of receiver transfers incident radiant energy to the working fluid to produce high-pressure, high-temperature steam through the means of a heat exchanger or a phase change of the working fluid itself. The working fluid can be water, air, or a salt material heated to a molten state. The output steam can facilitate a variety of applications, such as electrical power generation, enhanced oil recovery, and desalination. Heliostats are generally mounted on the ground in an area facing or surrounding the receiver tower. Each heliostat has a reflector: a rigid reflective surface, such as a mirror, that tracks the sun through the actuation of a heliostat drive mechanism about at least one axis. Sun-tracking involves orienting the reflector throughout the day so as to optimally redirect sunlight from the sun toward the receiver and maintain the desired temperature of the working fluid.
One approach to constructing a heliostat field is to utilize a small amount of comparatively large heliostats (e.g., greater than between 50 and 150 m2). In such a power plant, having a fewer number of heliostats may necessitate the manufacture of very precise, and thus very expensive, components for the positioning of the reflective surfaces. Another approach, however, is to use a large amount of comparatively small heliostats (e.g., between 1 and 10 m2), such as with reflective surfaces that measure between 1 and 3 m on each side. Such an approach may be more efficient at redirecting sun light because there are more individually adjustable reflective surfaces. In addition, smaller heliostats may be cheaper to produce and easier to assemble, decreasing installation time and operations costs. However, a plant comprising more heliostats will necessarily require the same amount of additional drive assemblies, increasing the number of repeated steps during installation. Accordingly, there is a need for heliostat assemblies that are both economical to manufacture and efficient to install.
A major cost driver in CSP plants is the cost of manufacturing, installing, and maintaining the components of the heliostat fields. Heliostat fields are typically deployed by installing ballast foundations into the ground and mounting the heliostats and reflectors thereto. Installing these ballast features may require significant ground preparation and heavy machinery, for example to dig holes of a suitable depth for structure posts. Deploying a plurality of heliostats may also be very time consuming if separate ballasts must be installed for each heliostat assembly, and the requisite labor can be a major contributor to operations and maintenance costs. If the interface between the heliostat and the ballast or structure to which it is mounted is complex, this can increase the time it takes to remove or replace heliostats in need of repair. Additionally, heliostats require power and data distribution means for actuation and control. Power and data is typically distributed to a heliostat drive via power and data distribution cables that may be routed through conduit, the ballast, or elements of the mounting structure. Feeding wires and cables through ballasts or structures may require additional setup time whenever a heliostat is installed or removed. This additional setup time becomes compounded during the installation or maintenance of a field comprising a plurality of heliostats, impacting labor costs. Accordingly, there is a need for heliostats having a drive assembly and mounting structure that are designed to minimize installation and replacement times.
Improved heliostat assemblies are described herein, wherein the assemblies are configured to facilitate rapid and repeatable installation (or removal) of heliostat drives onto (or from) heliostat structures. The improved heliostat assemblies thereby reduce construction and maintenance costs by reducing labor time and the mean time to repair a heliostat. To provide these advantages, the heliostat structures and drives may comprise compatible mechanical interface features that facilitate the installation of heliostat drives onto heliostat structures in one of a plurality of optional orientations utilizing a minimum of fasteners. In addition, the heliostat structures and drives may comprise cable management features for routing heliostat power and data cable connectors for convenient access to field power and data distribution cables. The heliostat assemblies of the present invention thereby obviate the need to route power and data distribution cables through heliostat ballasts or ground-mounted structures, reducing the time to install and remove units.
Heliostat assemblies according to an embodiment of the present invention may comprise: a drive chassis comprising a drive post having a groove, and a structure comprising a structure post having an alignment feature, wherein the drive post is inserted into the structure post and is aligned via the alignment feature. The alignment feature of the structure post may comprise a first tube end having a plurality of grooves, wherein the grooves are spaced equidistant from each other by an offset angle and define multiple heliostat drive orientations relative to the structure post. The drive post may further comprise a second tube end having a groove. The drive post attaches to the structure post via a plurality of fasteners that fit into the grooves of the alignment feature. The plurality of fasteners are spaced equidistant from each other by an offset angle such that the drive chassis can be installed in any of the multiple heliostat drive orientations as defined by the grooves of the alignment feature. The structure post may further comprise a contacting region having a smaller diameter than the first tube end, wherein the drive post makes contact with the contacting region.
The heliostat assembly may further comprise a capsule inserted into the drive post, wherein the capsule contains cable-mounting components and electronics components. The cable-mounting components may comprise cable connectors that egress from the capsule. The capsule may comprise a cable-positioning feature having a protrusion that orients the cable-mounting components at an acute angle relative to the capsule. The protrusion may be positioned within the groove of the drive post and within a groove of the alignment feature. The protrusion is further positioned between at least two of said plurality of fasteners and is spaced equidistant from said fasteners by an offset angle.
These and other features and advantages of the present invention are discussed or apparent in the following detailed description of the invention in conjunction with the accompanying drawings.
An improved heliostat assembly is described herein, with reference to
A heliostat assembly according to an embodiment of the present invention may comprise at least one heliostat drive installed onto a heliostat structure, as illustrated in
The alignment feature 113 may comprise a plurality of grooves 200 that allow for mounting of the heliostat drive, as illustrated in
A capsule 150 may be inserted into the drive post 160, and the drive post may be inserted into the structure post 113, as illustrated in
A cable-positioning feature 320 may be made integral with the capsule 150 to allow cable-mounting components 170 to exit the structure post 113, as illustrated in
The locations of the grooves 200 define multiple orientations of the heliostat drive when mounted on the structure, as illustrated in
The drive post 160 of the drive assembly 130 may further comprise a second tube end and a groove 170, as illustrated in
The structure post may further comprise a contacting feature 270 at the boundary between the alignment feature 113 and the tapered segment 115, as illustrated in
A capsule 150 may be inserted inside the drive post 160 as illustrated in
The capsule 150 may further comprise recessed portions into which the nuts 310 are embedded. The nuts may be threaded to interface with the fasteners of the drive post. In this way the same fasteners are used to stabilize the capsule within the drive post and fixedly mount the drive post to the structure post.
The cable-mounting feature 170 may comprise two cable ends, for example a female cable end 190 and a female cable end 195. The cable ends egress from the capsule and are guided by way of the cable-positioning feature 320 through the groove 170 of the drive post and a groove 200 of the alignment feature 113 at the end of the structure post. The cable ends may be of different lengths for easy identification; for example the female cable end may be longer than the male cable end. The cable positioning feature may also orient the cable ends 190 and 195 at an angle relative to the capsule via a protrusion.
Each heliostat assembly may additionally comprise a data and power connection for directing the drive to a desired orientation. The power connection may supply an energy path to a motor controller board of the heliostat drive. The motor controller board may transmit power to the electrical components of the drive assembly, such as motors that drive at least one transmission. The data connection may provide communication and control pathways to the heliostat drive control boards from a central or distributed controller or network. The power and data connections may comprise, for example, cables or wires that connect to the control board housed within the capsule.
Two inter-drive cables (not shown) may be connected to the cable- mounting components that egress from the capsule through the drive post groove and an alignment feature groove. The inter-drive cables may be used to connect the heliostat to other heliostats in the field, in this way power and/or data can be transmitted to heliostats connected in series. The inter-drive cables may be pre-wired to the cable management components, or they may be installed on site. One method of configuring the inter-drive cables is to provide one long cable and one short cable for each heliostat drive. The long cable may be configured to have sufficient length to reach the short cable of an adjacent heliostat drive on the same or neighboring structure. The inter-drive cables and cable-mounting components may be coated with material to enhance their lifetime when exposed to environmental conditions, such as a UV coating, plastics, metals, or other materials that can delay or prevent cable degradation.
Inter-drive cables may be attached to the structure with the use of one or more fastening devices. Potential fastening devices may include twist ties, clamps, clips, wires, adhesives, or another suitable method of attaching the cables to the structure. These fastening devices may help to minimize the movement of the cable in wind, and also act as strain relief by keeping the cables affixed to the structure.
When connecting inter-drive cables between heliostats, the cable may be left to hang between structure posts, or it may be held off the ground by a supporting feature. Examples of supporting features may include a wire, a rigid member, a flexible member, a slot, or an enclosed tube. The supporting feature be made integral with the structure or installed thereon. A supporting feature may be used to provide strain relief when a cable is run from one heliostat structure to another and may be made of a variety of materials, including but not limited to: metal, plastic, composites, or string. Alternatively, cables may be routed along the cross members between structure posts.
Various combinations and/or sub-combinations of the specific features and aspects of the above embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments may be combined with or substituted for one another in order to form varying modes of the disclosed invention. Further it is intended that the scope of the present invention herein disclosed by way of examples should not be limited by the particular disclosed embodiments described above.
The present application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/880,739, filed on Sep. 20, 2013, the entire disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61880739 | Sep 2013 | US |
